The mechanism of great Banda Sea earthquake of 01 February 1938: Applying the method of Preliminary Determination of Focal Mechanism <p> HR: <span class="hr"> 16:30h<br></span> AN: <span class="an"> S52K-03 <a href="../absbook/fm03-S52K.pdf">[PDF]</a><br></span> TI: <span class="ti"> The mechanism of great Banda Sea earthquake of 01 February 1938: Applying the method of Preliminary Determination of Focal Mechanism to a historical event<br></span> AU: <span class="au"> Reymond, D <br></span> EM: <span class="em"> reymond.d@labogeo.pf<br></span> AF: <span class="af"> LDG-CEA, B.P. 640, F-98713, Papeete French Polynesia <br></span> AU: <span class="au"> * Okal, E A<br></span> EM: <span class="em"> emile@earth.nwu.edu<br></span> AF: <span class="af"> Northwestern Univ., Locy Hall, Evanston, IL 60208 United States<br></span> AB: <span class="ab"> A moment tensor solution is derived for the 1938 Banda Sea earthquake, one of the largest events for which no definitive focal geometry has been published. We apply the PDFM method, which consists of inverting for a moment tensor using exclusively the spectral amplitudes of mantle waves, while discarding the phase information affected by uncertainties in relative timing between historical records. From a dataset of 17 records at 7 stations, we obtain a robust solution, featuring a very large moment of 8.4*10**28 dyn-cm, the centroid depth being constrained at 60 km by minimizing the r.m.s. residual of the inversion. The method involves an inherent two-fold 180-deg. indeterminacy on strike and slip, which is lifted by the polarization of long-period body waves read individually on original records, resulting in a mostly thrust-faulting mechanism (strike: 276 deg.; dip: 63 deg.; slip: deg.). This confirms the event as ranking among the ten largest moments ever published. Its deeper than normal focus agrees well with the minor level of reported damage, and with the generation of a relatively benign tsunami. The 1938 event shares its compressional axis with that of the smaller and deeper 1963 shock to the Southwest, which probably expresses coherence in the regional contortion of the subducting Australian plate lithosphere. <br></span> DE: <span class="de"> 7215 Earthquake parameters<br></span> DE: <span class="de"> 7255 Surface waves and free oscillations<br></span> SC: <span class="sc"> Seismology [S]<br></span> MN: <span class="mn"> 2003 Fall Meeting<br></span></p></body></html>